This invention relates to a traveling device movable along a straight or a curved elongated member by alternately supplying and exhausting a pressurized fluid into and from the elastic member which expands radially outwardly and contracts in axial directions when being supplied with the pressurized fluid.
In chemical plants, nuclear power stations and the like, there are a great many pipe lines effectively connected for chemical reaction, energy conversion processes and the like. In order to operate these plants safely and effectively, it is necessary to maintain and inspect the inside and outside of these pipe lines periodically.
However, it is sometimes impossible for an operator to directly inspect the inside of the pipe lines due to their small diameters and external conditions.
In such a case, damage of the pipe lines and existence or amount of substances accumulated in the pipe lines have been inspected by a traveling device having wheels or pawls and driven by an electric or hydraulic motor, which was provided with monitor means such as small type television camera or fiber scope.
With such a hitherto used traveling device, as the electric or hydraulic motor is used as driving means, the traveling device is heavy and bulky so that an applicable range is limited. In addition, as the weight of the main body of the traveling device is heavy in comparison with the driving power, the traveling area is limited to horizontal portions or slightly inclined or curved portions of pipe lines. Moreover as the traveling device itself is rigid in construction, it is difficult to move along curved portions of the pipe lines.
Furthermore, the electric or hydraulic motor as driving means tends to cause sparks and heating in operation so that the use of such a motor is limited in chemical plants including petroleum refineries treating inflammable or explosive materials.
A traveling device having an elastic contractible body as shown in FIG. 1 has been proposed in Japanese Patent Application Laid-open No. 63-91,555. This device includes support members 4 supporting both ends of the elastic contractible body, and anchoring means 6 arranged on the support members 4 and adapted to be alternately expanded by supplying and exhausting a pressurized fluid into and from the elastic contractible body 2 so that the anchoring means are brought into engagement with an inner circumferential surface of a pipe to perform advancing or retracting movement of the traveling device. This traveling device uses an elastic contractible body of the air-bag type as an actuator. Therefore, the traveling device is small and light weight and superior in explosion-proofness and has other various advantages as a traveling device. Reference numeral 8 denotes an elastic member arranged between the support members 4 which returns to an original length on exhausting the pressurized fluid from the elastic contractible body to move the support members toward and away from each other.
However, the traveling device movable in a pipe was intended to be moved along a substantially straight line or a curved line having a large radius of curvature. This traveling device cannot move when it encounters a crossing portion, for example, a crossed branched portion or T-shaped branched portion or a curved portion having a small radius of curvature.
Moreover, even at a crossed portion where two pipes cross at a relatively small angle, it is difficult to bring one of anchoring means 6 into engagement with an inner circumferential surface of the pipe sufficiently. Therefore, reliable traveling of the device could not be guaranteed.